Bagitley



Jan. 27, 1931.

F. SHEDDEN ET Al.

Filed Aug. 13, 1927 INVENTORS FRANK SHEDDEN ALBERT ERNEST DELPH NOEL GREGORY BAGULEY her, and with a katharometer,

Patented Jan. 2.7, 1931 UNITED sTAT-as; orrre FRANK sHEnn or oovENTnY, ALBERT ERNEST: rinter, on BooKI G, ANni oriL canteens BAG or COVENTRY, E er n,,assIG ons To COUBTAULDS I .I1'vI-,

Iran, or LONDON, E G A D MANUFACTURE AND PRODUCTION or ARTIFICIAL ,sI K A arrAm UsT Innnron Application filed. August 13, 1927, Serial No. 212,846, and in Great Britain October 4, 1926; This invention relates to the manufacture of artificial silk by the method known as dry spinning, that is to say, the method in which a solution of a cellulose derivative such as a cellulose ester or cellulose ether in a volatile solvent is extruded through fine orifices into a gaseous atmosphere, whereby the solvent is vapourized,leaving the cellulose ester or cellulose ether in the form of filaments. For the sake of clearness we'will describe this invention with reference to the manufacture of artificial silk by spinning a solution of cellulose acetate in acetone into an atmosphere of warmair which will become to some extent laden with acetone vapour, before it leaves the spinning chann her, but it will be understood that the in vention is not limited to the'use of this particnlar cellulose compound or solvent or evaporative medium, as the term artificial silk is intended to include generally all the types of artificial filaments which can be produced by the dry spinning process. hen producing artificial silk from asolution of cellulose acetate in acetone according to the dry spinning method, the character ofthe silk; is liable to vary according, to the greater or smaller content of acetone vapour katharometer should comprise two' small lengths or coils of wire which areheatedby means of an electric, current. The two lengths or coils of WlI'G- are placed. in two arms of a VVh'eatstone bridge system,- so that their resistances can be compared, one of the coils being enclosed in an atmosphereof constant compositionwhil'e the other is exposed to the action of the gaseous mixture contained in" the spinning-chamber. Accordeous mixture, the rate of loss. of heat-from the said coil: will vary, and consequentlythe d-iiierence between the resistance of the coil exposed to the gaseous mixture, andthe' resistance or the other coil exposed-to-a constant atmosphere, which can be measured by the lvheatstonecbridge method or indicated by means of a/galvanometer or other instrument-such as'is 'usedxin connection with a lNheatstonebridge, will enable the operator to-ascertain whether the content are remaining constant in each particular spinning chamber, and also whether such conditions in one spinning chamber are mo -cor less the sameas 'orequal 'to the condi'tions obtaining in the other spinning chamin the air in the spinning chamber, other i hers. It is not necessary to ascertain the abtors remaining-constant. Thus; with i h g solute-value of the vapor 'content butsimply Q P P 34 illthe neigh an -"index of whether or not it is varying.

bourhood ofthe jet, the filamentsare gen- Th b olut value could, of course, be oberally more b t0 have s tcrOSS- tained byproper calibration}of the recordsection and a greater lustre than when the proportion of f acetone vapour is lower. Vhen it is desired to produce one particular quality of artificialsilk the conditions as regards the acetone content in the spinning chamber shouldbe kept constant and further such conditions shouldvbe maintained as "nearly as possible the same in all; the spin ning chambers in which it is desired to pro-' duce the same'quality of artificial silk. Vi e have now iound that we are able to maintain constant in a spinningchamber the conditions as regards the acetone vapour content by making use of a chamber provided with a valve or other means for regulating the flow of air-into or out of the cham- The said;

ing instrument. In this: case, expressions such as valueof the Vapor content mean either the absolute va or even the mere fact 0 standard Should he find that the c ond iti'ons have varied "illiollllllfl standard which, at themom'cnt, itis desired' to maintain, he will, by'making suitablea in the quantity of air'entering or leavingthe spinning chamber, beable to regulate such. amount of air entering 'or leaving the spinning: chamber, so as tobringbackagain"the conditions as regardsv the? acetonevapour content to'the standard which isfre'quired. The: acetone vapour content inside the spin ning chamber may, of'course, ingto the conditions US$1 Fblinstance,

var-y according to the content of: acetone in the said gas} I difierence-ot resistance conditions as regards the acetone'vapour r '85 lue,a compariat1ve.value if a variation from djustinents for instance of. cellulose acetate solution, the extrusion of Iii 1 obtaining in one spinning chamber 1 tothos'e of aoth'er spinningchamber or other 'vcnient for example t I to bebrought to the 'katharometcr, from the vapour is practically uniform a larger quantity of such cellulose acetate solution will be necessary, with the consequent evaporation of a larger quantity of acetone, so that ifit be desired to maintain the actual percentage of acetone in the gas leavingthe spinning chamber, thesame as I when a thread of lower denier is being spun, it will be desirable in the case of the heavier denier to pass a greater current of air through the apparatus.

It will, of course, be understood that the proportion of acetone contained in the air of the. spinning chamber .(llilfil'S at different parts of the spinning. chamber. For example, in the casein which the spinning nozzle is situated at the top of the chamber so thatthe threadstravel downwards and are taken out at the lower endof the chamber, while the air travels in the opposite direction, that is-to say, enters at the lower end and leaves at; the upper end of the chamber, if fresh air'is allowed to enter the chamber :at the lower end, the acetone content just at the point of entry Willbe practically nil. As this air'as cends insidethe chamber, it will gradually take more and more acetone from the descending thread, and the acetone con- ,tentwill, consequently, increase,.reaching a maximum as it passes the jet where the acetone solut on of cellulose acetateisbemg ex- ,truded'into the chamber and theevaporat on lot the acetone commences. In order, there fore, to ascertainwhether the conditions as regards the acetone vapour content in the mixed atmosphere of the chamber is remaining constant,it will be necessary in the case in which thekatharometer itselfis placed inside the spinning chamber, that the saidkatharometer should remain in one position [in the spinning chamber and should notbe moved about from place to place in the said chamber. If, however, the katharometer be placed. outside the spinning chamber and a part oi"- the acetone-laden air is taken fromthe chamber and brought to the katharometer, it

will be necessarythat this aeetone-ladenair be takenefrom the spinning chamber under uni-formconditions, for instance, it should always be taken from the. same place inside the chamber and at the same rate. It is con- 0 take the air, which is narrow exit tube which is attached to or -i0rmsthe upperlpart of the spinning chamber, since here themixture of air'and acetone and repre sents the average composition of contents of the. spinning chamber.

Similarly in order :to ascertain Whether the conditions are similar ch'ambers'of the jet or series, it is desirable 3 tee gaseous that the katha-rometers should be placed in approxin'iately the same position in each of the spinning chambers or that'the acetoneladenair to be. tested should be taken under similar conditions from each chamber of the saidseries and again in this latter case it is y convenient to take the gas from the narrow pipe forming the upper eXit' of each'zsuch chamber. Whether the instrument is placed "within the chamber'or is outside of it, though connected in either case to receive vapor laden gas therefrom, the important thing is to as- V certain the value of the vapor content or" the gas at a resprescntative point so that'the value ascertained may be a reliableindex of the condition ofthe gaseous mixture in the neighby suitablyarranging the pipes conveying the gas from one or other chamber can be conveyed to the katharometer the gas so that as desired. I v 1 I The apparatus whichhas been described above underuthe name katharometer is die scribed N0.-124,453, and in S Patent 1,304,208. This name is also used in connectionwith the specific apparatus in the Proceedings. of the Royal Society 1920, volume; 97, page 213.

V The drawing,accompanying this specification illustrates in vertical cross-section apv paratus aecording to this invention. In the said drawing chamber, Bfthe through which thesolution of the cellulose derivative is extruded, C isa holeat the lower end of the spinning chamber through which Air is drawn into the chamber A through the hole C, and out through the ductF, which is in the specification of British,Patent the thread D passes onto'the roller A represents the spinning, nozzle containing small holes provided with an adjustable valve G, by"

means of which the quantityof gas passing through the chamber may be regulated. The

tube His provided with its open end in close the spinning nozzle. B, While proximity to the other end is attached to the katharometer K. A further tube L attached to the katharomcter is provided, and by gentle suction" to the tube L, vapor-laden gas is drawnfromthe' proximity of the spinning nozzle 13 through the tube I-I into the katharometer, which can be so calibrated as to indicate the percentage of solvent vapor contained in the gas. r

W hat we claim is 1. The methoo of gaining uniformity of product in the manufacture of artificial "silk by forming,in the'presence of a heated gas,; 7 a get or a cellulose derivative contained in applying a a volatile solvent whereby the solvent va-- porizes giving a vapor content to the heated gas, the steps of the method being the ascertainment of the value of the vapor content of the gas at a point that is representative of the condition of the gaseous mixture in the neighborhood of the jet, and a maintenance of the said content at a uniform value by regulating the supply of gas to the spinning chamber.

2. Apparatus comprising a spinning chan'r,

ber for the manufacture of artificial silk, means therein for forming a jet of a cellulose derivative contained in a volatile solvent, a duet for delivering therefrom the gas laden with vapor from the solvent, means for regulating the supply of gas passing through said chamber and means for ascertaining the val.- ue of the vapor content of said gas at a point that is representative of the conditions of the gaseous mixture in the neighborhood of the jet.

8. Apparatus comprising a spinning chamber for the manufacture of artificial silk, means therein for forming a jet of a cellulose derivative contained in a volatile solvent, a duct for delivering therefrom the gas laden with vapor from the solvent, means for regulating the supplyof gas passing through said chamber and a katharometer connected to receive vapor laden gas from a point that is representative of the condition of the gaseous mixture in the neighborhood of the jet.

In testimony whereof We have signed our names to this specification.

FRANK SHEDDEN. ALBERT ERNEST DELPH. NOEL GREGORY BAGULEY. 

